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Histology Winter Semester > Epithelial Tissue (Lectures 4 and 5) > Flashcards

Epithelial Tissue (Lectures 4 and 5) Flashcards

1
Q

What are the specialised cell junctions?

A

Cells are closely apposed and adhere to one another by means of specific cell adhesion molecules (CAMs).

Specialised cell junctions:

OCCLUDING JUNCTIONS - Link forming an impermeable barrier, tight junction.

ANCHORING JUNCTIONS - Provide mechanical stability by linking of the cytoskeleton of one cell to the cytoskeleton of adjacent cell.

  • Zonula adherens (focal contacts) - actin filaments
  • Macula adherens/desmosome (hemidesmosome) - intermediate filaments

COMMUNICATING JUNCTIONS - Gap junctions – allow selective diffusion of molecules between adjacent cells. (Cell to extracellular matric junctions).

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2
Q

Explain cell polarity.

A

Free surface or apical domain:

Special structural surface modifications

Microvilli:

  • Cytoplasmic processes (core consisting of actin filaments).
  • Closed packed microvilli = brush border (absorptive epithelium).

Stereocilia:

  • Long immotile microvilli (hair cells of the inner ear, epithelium of the ductus epididymidis and ductus deferens).

Cilia:

  • Motile cytoplasmic processes (consisting of microtubule axoneme, basal bodies).
  • Epithelium of respiratory ways, and uterine tube.

Lateral domain:

  • In close contact with the opposed lateral domains of neighboring cells.
  • Presence of unique proteins, cell adhesion molecules (CAMs).
  • Specialized cell-to-cell junctions (occluding, anchoring, communicating).
  • Folding - invagination and evagination (interdigitation) of lateral cell membrane.

Basal domain:

  • Attached to the basement membrane, cell-to-extracellular matrix junctions (focal contacts, hemidesmosomes), basal cell membrane infoldings (ion – transporting cells: striated ducts of salivary glands, kidney tubules).
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3
Q

How can epithelium be classified according to the arrangement of cells?

A

PLANAR = cells form tightly cohesive sheets traditional nomenclature is based on:

  • Cell shape –> squamous, cuboidal, columnar
  • Number of layers –> simple, stratified, pseudostratified

TRABECULAR = cells are arranged in cords or plates (liver, endocrine glands).

RETICULAR = cells form three-dimensional network (stroma of thymus, epithelium of crypts in tonsils, stellate reticulum of enamel organ).

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4
Q

Classification of epithelium according to functional specialization.

A
  • Covering epithelium
    • Simple squamous, cuboidal, columnar, pseudostratified columnar
    • Stratified squamous, columnar
    • Transitional epithelium (urothelium)
  • Secretory epithelium
    • Exocrine and endocrine
    • Polarisatin of cells
    • Mechanism of secretion: merocrine, apocrine, holocrine
  • Absorptive epithelium
  • Respiratory epithelium
    • Exchange of respiratory gases, in the lung alvioli
  • Sensory epithelium
    • Cells react on the external stimuli by change of membrane potential.
    • Primary and secondary sensory cells.
  • Myoepithelium
    • Cells with ability to contract
  • Germinal epithelium
    • Production of cells (seminiferous epithelium of testis produce spermatozoa).
  • Ion-transporting epithelium
    • Modificaiton of the basal cell surface
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5
Q

What is this slide?

A

LIVER

Trabecular epithelium

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6
Q

What is this slide?

A

Suprarenal gland

Trabecular epithelium

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7
Q

What is this slide?

A

Simple squanous epithelium

Mesothelium

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8
Q

What is this slide?

A

Simple cuboidal epithelium

Thyroid gland

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9
Q

What is this slide?

A

Basement membrane (kidney, PAS reaction).

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10
Q

What is this slide?

A

Simple squamous epithelium (kidney, HE)

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11
Q

What is this slide?

A

Simple cuboidal epitheloim (Heidenhain H)

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12
Q

What is this slide?

A

Simple columnar mucus secreting epitheloim (alcian blue, nuclear red).

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13
Q

What is this slide?

A

Small intestine

Villi

Simple columnar epithelium

PAS reaction

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14
Q

What is this slide?

A

Pseudostratified columnar ciliated epithelium (trachea, green trichrome)

Type of epithelium in which all cells lie on the basal lamina, but only columnar cells reach lumen.

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15
Q

What is this slide?

A

Stratified columnar epithelium

Duct of a sweat gland

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16
Q

What is this slide?

A

Parotid gland

H and E

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17
Q

What is this slide?

A

Oesophagus

HE

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18
Q

What is this slide?

A

Pseudostratified ciliated epithelium

Trachea

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19
Q

Explain transitional epithelium

A
  • Lines urinary passages, is a special form of the covering epithelium.
  • According of arrangement of cells - psudostratified epithelium.
  • Is impermeable for salts and water, is able to adapt to the distension of organ.
  • Adaptability of epithelium to distension is enabled by a unique structure of luminal cell membrane that exhibits modified areas – plaques.
  • Plaques appear to be more rigid and thicker (12 nm) and actin filaments are attached to the inner surface of plaques.
  • In the undistended epithelium plaques infold inward the cytoplasm and appear as fusiform vesicles – their lumina, however, are in continuity with the cell surface.
  • As organ distends, the fusiform vesicles unfold and become part of the surfaceas the cell streches and flattens.
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20
Q

What is this slide?

A

Transitional epithelium

Non distended state - urinary blasser

AZAN

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21
Q

What is this slide?

A

Urinary bladder

HE

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22
Q

What is this slide?

A

Respiratory epithelium (lung)

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23
Q

What is this slide?

A

Respiratory epithelium

24
Q

What is this slide?

A

Respiratory epithelium

25
Q

Explain the structure and function of sensory epithelium.

A
  • Sensory epithelium consists of sensory cells and supporting cells.
  • Sensory cells are receptors, convert external stimuli into electric impulses.

Classification according stimulus:

Photoreceptors = rods and cones of the retina
Chemoreceptors = olfactory cells (smell, olfaction) and taste cells Mechanoreceptors = hair cells of the inner ear (auditory/sound perception and vestibular/balance systems)

Classification according structure:

Primary sensory cells –> have axon; rods, cones, and olfactory cells Secondary sensory cells –> have no axon; hair and taste sensory cells

SENSORY ORGANS

  • Taste buds
  • Olfactory epithelium
  • Eye (retina)
  • Inner ear –> Corti organ and vestibular apparatus (maculae staticae and cristae ampullares)
26
Q

What is this?

A

Olfactory epithelium

Olfactory cells

27
Q

Explain rods and cones.

A

Rod:

  • Thin elongated cell
  • Photoreceptor
  • Part has red shape
  • Rods are more sensitive to light
  • Prgment rhodopsin (visual purple)
  • 120 million rods

Cones:

  • Photoreceptor part has cone shape.
  • Each cone is specialised to respond to one of three colours - red, green or blue.
  • Pigment = iodopsins.
  • Contrary to rod the interior of cone discs is continuous with the extra cellular space.
  • Outer limiting membrane (red lining is formed by a row of zonulae adherentes (ZA) between Muller’s cells and photoreceptors.

OS = Outer segment –> Has cylindrical shape, contains horizontally flattened membrane discs.

C = Connecting stalk with cilium.

BB = Basal body of cilium.

IS = Inner segment (metabolic region), contains protein synthesis organelles (Golgi complex, rER, free ribosomes, mitochondria).

OF = Outer fibre

N = Cell body with nucleus

IF = Inner fibre - axon

P = Presynaptic part (synapse with bipolar neurons).

28
Q

Describe sensory epithelium

A
  • Sensory epithelium of the inner ear consists of sensory hair cells and supporting cells.
  • Hair cells are mechanoreceptors.
  • Apical surface carries highly organised system of steriocilia and one kindocilium.
  • Steriocilia are rigid structures and have mechanial-gated ion channels on their tops.
  • Flection of stereocilia to kinocilium causes excitation (depolarisation of the plasma membrane).
29
Q

Describe myoepithelium

A

Myoepithelium is a contractile epithelium which contains actin and myosin myofilaments.

Surround the glandular epithelial cells in the salivary glands, eccrine and apocrine glands in the skin, mammary gland, dilator pupillae muscle.

30
Q

What is this slide?

A

Seminiferous tubule

31
Q

What are the two types of glandular epithelium?

A

Exocrine

Endocrine

32
Q

What is this slide?

A

Goblet cells

Large intestine

PAS reaction

33
Q

What is this slide?

A

Goblet cells

Large intestive

Alcian blue

Nucear red

34
Q

Describe serous cells

A

Serous cells (serous acini, serous demiluni):

  • Protein secreting cell (secretion = enzymes, water ions)
  • Basl cytoplasm - basophilic, RER, motochondria
  • Golgi complex in supranuclear location
  • Apical cytoplasm - secretory granules (usually basophilic)
35
Q

Describe mucous cells

A

Mucous cell (mucous tubules):

  • Low columnar cell
  • Flattened condensed nucleus
  • Cytoplasm is fulled with mucinogeous granules
  • Mucus/mucin-producing cell
  • Staining - PAS reaction, alcian blue
36
Q

What are the different kinds of ducts?

A
37
Q

What is this slide?

A

Submandibular gland (HE)

A = serous acinus

T = mucous tubule

E = striated duct lined with a simple columnar, ion transporting epithelium

O = eosinophilic basal striation

38
Q

What is this slide?

A

Parotid duct

39
Q

What is this slide?

A

Submandibular gland

40
Q

What is this slide?

A

Sublingual gland

41
Q

What is this slide?

A

Parotid gland

42
Q

What is this slide?

A

Striated duct

43
Q

What is this slide?

A

Interlobular ducts

44
Q

What is this slide?

A

Interlobular duct

45
Q

Describe this scheme of an endocrine cell

A

Polarity of the secretory epithelium

A cell (glucagon producing) of Langerhans islet of the pancreas.

N = nucleus

Nu = nucleolus

M = mitochondria

S = secretory granules

BL = basal lamina

rER = Rough endoplasmic reticulum

P = plasma membrane

Cap = blood capillary

Arrow = exocytosis of glucagon into bloodstream

46
Q

What is this slide?

A

Pancreas

47
Q

What is this slide?

A

Islets of Langerhans

48
Q

What are the types of secretion?

A
49
Q

What is this slide?

A

Sebacious gland

50
Q

What is this slide?

A

Sebacious gland

51
Q

What is this slide?

A

Sebacious gland

52
Q

What is this slide?

A

Merocrine sweat gland

53
Q

What is this slide?

A

Merocrine sweat gland

54
Q

What is this slide?

A

Merocrine sweat gland

55
Q

What is this slide?

A

Apocrine gland - skin

56
Q

What is this slide?

A

Apocrine gland - skin

Histology Winter Semester (10 decks)

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